CNN  — 

A 69-year-old Jewish man died after suffering a head injury Sunday following an “interaction” with a pro-Palestinian demonstrator during dueling rallies in Southern California, the Ventura County Sheriff said Tuesday, adding authorities had not ruled out the possibility of a hate crime.

The death of the man, identified by law enforcement as Paul Kessler, has been ruled a homicide, authorities said. The 50-year-old suspect was detained but later released and has not been arrested, Ventura County Sheriff James Fryhoff said in a news conference, and Kessler’s death remains under investigation.

Witnesses say Kessler was “involved in a physical altercation” with at least one counterprotester while pro-Israeli and pro-Palestinian rallies were being held in Thousand Oaks, the Ventura County Sheriff’s Office said in a news release Monday.

“There was clearly an interaction between the two, but what that level of interaction is, is still unclear,” Fryhoff said, asking members of the public who witnessed the incident or had footage to contact authorities.

Kessler, the sheriff said, was supporting Israel at the demonstrations – two among the many that have sprung up in cities across the US, either in support of Israel or to protest its retaliation for the October 7 Hamas attacks, which killed more than 1,400 people.

More than 10,000 people have been killed in Gaza since Israel launched its military offensive a month ago, the Palestinian Ministry of Health in Ramallah said Monday, drawing from sources in the Hamas-controlled enclave. Israeli airstrikes have hit schoolsrefugee camps and ambulances.

What happened prior to Kessler’s head injury is unclear, Fryhoff said Tuesday, pointing to conflicting accounts from pro-Israeli and pro-Palestinian witnesses.

“My contention is that we’re still waiting to see evidence of what occurred in that interaction, and whether or not there was a blow to the face that caused the fall, or if Mr. Kessler fell, without that being the precipitating event,” Fryhoff said.

One video filmed at the scene and shared online shows Kessler lying on his back on the sidewalk, with blood on his face and on the ground. He places his hands on his head as a woman with a Palestinian flag on her back and a man lean over him, trying to help, the video shows.

The footage does not show the altercation that led to Kessler’s injuries.

The suspect, who has not been publicly identified, was interviewed at the scene, Fryhoff said. He was cooperative and told authorities he was involved in the altercation with Kessler, Fyhoff said. The suspect also said he was among the people who called 911 so Kessler could receive medical attention.

Kessler was still conscious and responsive when Ventura County Sheriff deputies arrived on the scene shortly before 3:30 p.m. Monday, Fryhoff said. Kessler was given medical aid by the Ventura County Fire Department and taken to the hospital, where he was listed in critical condition, the sheriff said.

It was just before 3 a.m. Monday that the hospital informed the sheriff’s office Kessler had died, Fryhoff said.

Late Monday afternoon, detectives conducted a traffic stop on a vehicle driven by